A kind of against the type of liquid flow battery test system
By using a towed flow battery testing system, two battery packs under test are connected to a DC/DC converter to enable the flow and transfer of electrical energy between the battery packs. This solves the problems of energy waste and high cost in flow battery testing and achieves an efficient and low-cost testing process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- HAICHU TESTING (DALIAN) CO LTD
- Filing Date
- 2025-05-30
- Publication Date
- 2026-05-29
AI Technical Summary
Existing flow battery testing systems suffer from energy waste and high testing costs in high-power stack testing, especially when multiple test points are charged and discharged simultaneously, which requires a huge amount of power capacity and leads to increased electricity costs.
A towed flow battery testing system is adopted, in which two battery packs under test are connected to DC/DC converters respectively. When one battery pack under test is discharging, the electrical energy is input to the other battery pack under test through the other DC/DC converter for charging. The state of charge is monitored by a control module and BMS to ensure the smooth progress of the charging and discharging process and the efficient use of electrical energy.
It significantly reduces energy consumption in converting electrical energy into heat, lowers cooling and grid expansion costs, improves testing efficiency and accuracy, and reduces electricity costs.
Smart Images
Figure CN224303822U_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of flow batteries, specifically relating to a test system for a towed flow battery. Background Technology
[0002] A flow battery consists of a stack unit, electrolyte, electrolyte storage and supply unit, and management and control unit. It is a high-performance battery that utilizes separate, independently circulating positive and negative electrolytes. The interconversion of electrical and chemical energy is achieved through reversible redox reactions (i.e., reversible changes in valence states) between the active materials in the positive and negative electrode electrolyte solutions. During charging, oxidation occurs at the positive electrode, increasing the valence state of the active materials, while reduction occurs at the negative electrode, decreasing the valence state. The discharge process is the reverse. The positive and / or negative electrode electrolyte solutions are stored in external tanks and transported to the stack for reaction via pumps and pipelines. Flow batteries are characterized by high capacity, wide application range, and long cycle life.
[0003] Charge-discharge testing of flow batteries is a crucial step in the battery stack production line. After the battery stack is assembled, charge-discharge tests are conducted to verify whether the performance of the produced battery stack meets the design requirements, thereby providing users with more reliable, safer, and more efficient products.
[0004] Currently, the power of flow battery stacks ranges from tens of kilowatts to hundreds of kilowatts, representing a significant increase in the power of a single stack. On the testing line of the stack production line, there are multiple testing points. Traditional flow battery testing systems typically use resistance discharge for testing, during which electrical energy is consumed as heat. This not only wastes energy but also generates a large amount of heat, increasing cooling costs and consequently raising testing costs. Furthermore, the simultaneous charge-discharge testing of high-power stacks at multiple testing points creates a huge demand for power capacity, further contributing to high electricity costs.
[0005] Therefore, it is necessary to optimize the flow battery testing system to reduce energy waste and lower testing costs. Utility Model Content
[0006] This application provides a towed flow battery testing system that solves the problem of excessive energy waste during flow battery testing and reduces testing costs.
[0007] The technical solution adopted in this application is as follows:
[0008] A test system for towed flow batteries is provided for simultaneously charging and discharging two battery stacks under test. The system includes an AC / DC converter connected to a power grid, a DC / DC converter connected to the AC / DC converter, and a battery stack under test connected to the DC / DC converter. The DC / DC converter includes a first DC / DC converter and a second DC / DC converter. The battery stack under test includes a first battery stack connected to the first DC / DC converter and a second battery stack connected to the second DC / DC converter. The first DC / DC converter is connected to the second DC / DC converter.
[0009] It also includes a control module and a BMS connected to the control module. The BMS is connected to the battery pack under test. The BMS is configured to send the charging and discharging data of the battery pack under test during the charging and discharging process to the control module. The control module is configured to control the start-up of the AC / DC converter and the DC / DC converter based on the data obtained by the BMS.
[0010] Preferably, a first transmission line is provided between the first DC / DC converter and the first battery pack under test, a second transmission line is provided between the second DC / DC converter and the second battery pack under test, and a third transmission line connecting the first transmission line and the second transmission line is provided between the two DC / DC converters. Both the first DC / DC converter and the second DC / DC converter include a discharge state and a charging state, and the control module is configured such that when one of the DC / DC converters is in the discharge state, the other DC / DC converter is in the charging state.
[0011] Preferably, the BMS is connected to the first battery pack under test and the second battery pack under test respectively, and the charge / discharge data includes the state of charge of the first battery pack under test and the state of charge of the second battery pack under test.
[0012] Preferably, the control module is connected to the DC / DC converter, and the control module is configured to shut down the corresponding DC / DC converter in the discharge state and stop discharging when the state of charge of the battery pack under test in the discharge state reaches a preset lower limit state of charge.
[0013] Preferably, a fourth power transmission line connected to the third power line is provided between the AC / DC converter and the DC / DC converter. The control module is configured to turn on the AC / DC converter and connect it to the DC / DC converter in the charging state after the battery pack under test stops discharging in the discharging state, and to replenish the battery pack under test in the charging state through the fourth power transmission line.
[0014] Preferably, the battery pack under test includes an initial state, and the control module is configured to, in the initial state, turn on the AC / DC converter and the first DC / DC converter, while turning off the second DC / DC converter, so that the first battery pack under test is charged to a first upper limit state of charge.
[0015] Preferably, the BMS is configured to acquire the state of charge of the first battery pack under test and feed it back to the control module when the battery pack under test is in the initial state, and to shut down the AC / DC converter when the state of charge of the first battery pack under test reaches the first upper limit state of charge.
[0016] Preferably, both the first DC / DC converter and the second DC / DC converter are bidirectional DC / DC converters.
[0017] Preferably, both the first battery pack under test and the second battery pack under test include: a battery stack, a positive electrode reservoir connected to the positive electrode of the battery stack and a negative electrode reservoir connected to the negative electrode of the battery stack, a valve and a circulation pump located on the connection line between the positive electrode reservoir and the negative electrode reservoir and the battery stack, each battery stack being connected to the corresponding DC / DC converter, and the BMS being configured to acquire the state of charge of the two battery stacks during the test.
[0018] Preferably, the valve is a ball valve, and the ball valve and the circulating pump are always in the open state during the test.
[0019] Due to the adoption of the above technical solution, the beneficial effects achieved by this application are as follows:
[0020] (1) The present application proposes a towed charging and discharging test system based on the characteristics of flow batteries. The two battery packs under test (i.e. the first battery pack under test and the second battery pack under test in this proposal) are set up in a towed structure and connected to DC / DC converters respectively. When one battery pack under test is discharging, the released electrical energy is input to the other battery pack under test by turning on the other DC / DC converter, so as to realize the simultaneous discharge test and charging test of the two battery packs under test respectively.
[0021] Compared to resistive discharge, this solution significantly reduces energy consumption in converting electrical energy into heat, thus reducing energy waste and lowering cooling costs. Furthermore, this solution utilizes two connected DC / DC converters to enable the flow of electrical energy between the two battery packs under test. When one battery pack discharges, the released energy is used to charge the other, eliminating the need for multiple discharges and charges for each individual battery pack. This reduces the need for grid expansion, further lowering expansion costs and electricity expenses, and facilitating wider adoption.
[0022] (2) The solution of this application sets up a control module and a BMS to monitor the state of charge of the battery pack under test in real time during the test process, so as to ensure the smooth progress of the charging and discharging process. The control module controls the activation of the first DC / DC converter and the second DC / DC converter. During the charging and discharging process of the first battery pack under test and the second battery pack under test, the BMS monitors the state of charge of the first battery pack under test and the second battery pack under test and transmits it to the control module to determine whether the state of charge of the two battery packs under test is changing normally, so as to ensure the smooth progress of the test process.
[0023] (3) The proposed solution uses a BMS to monitor and obtain the state of charge of the first and second battery packs under test. During the charging and discharging process, the DC / DC converter corresponding to the discharging battery pack is turned off when the preset lower limit of the state of charge is reached, thus stopping the discharge. Since there is inevitably energy loss during the discharge process, the released energy cannot be fully input to the other battery pack under test. To ensure the accuracy of the test results, the charging battery pack under test is recharged through the power grid to reach the preset upper limit of the state of charge. The preset lower limit of the state of charge and the preset upper limit of the state of charge are set in advance according to the test requirements. For example, the preset lower limit of the state of charge is set to 10%, and the preset upper limit of the state of charge is set to 90%. The specific settings can be made according to the actual test requirements. Attached Figure Description
[0024] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:
[0025] Figure 1 This is a schematic diagram of a towed flow battery in one embodiment of the present invention.
[0026] Explanation of reference numerals in the attached figures:
[0027] 1-Power grid, 2-AC / DC converter, 3-First DC / DC converter, 4-Second DC / DC converter, 5-First battery pack under test, 51-No. 1 battery stack, 52-Positive electrode storage tank, 53-Negative electrode storage tank, 6-Second battery pack under test, 61-No. 2 battery stack, 7-Circulation pump, 8-Ball valve, 9-Control module, 10-BMS. Detailed Implementation
[0028] To more clearly illustrate the overall concept of this application, a detailed explanation is provided below with reference to the accompanying drawings.
[0029] Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below. It should be noted that, unless otherwise specified, the embodiments of this application and the features thereof can be combined with each other.
[0030] Furthermore, it should be understood in the description of this application that the terms "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.
[0031] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0032] In this application, unless otherwise expressly specified and limited, the "above" or "below" of the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.
[0033] This application provides a testing system for towed flow batteries, such as... Figure 1 As shown, a method for simultaneously charging and discharging two battery packs under test includes an AC / DC converter 2 connected to a power grid 1, a DC / DC converter connected to the AC / DC converter 2, and a battery pack under test connected to the DC / DC converter. The DC / DC converter includes a first DC / DC converter 3 and a second DC / DC converter 4. The battery pack under test includes a first battery pack 5 connected to the first DC / DC converter 3 and a second battery pack 6 connected to the second DC / DC converter 4. The first DC / DC converter 3 is connected to the second DC / DC converter 4.
[0034] It also includes a control module 9 and a BMS10 connected to the control module 9. The BMS10 is connected to the battery pack under test and is configured to send the charging and discharging data of the battery pack under test during the charging and discharging process to the control module 9. The control module 9 is configured to control the start-up of the AC / DC converter 2 and the DC / DC converter based on the data obtained by the BMS10.
[0035] The control module in this application can be a computer program.
[0036] This application proposes a counter-charge and discharge test system tailored to the characteristics of flow batteries. Two battery packs under test (i.e., the first battery pack 5 and the second battery pack 6 in this proposal) are configured in a counter-charge structure and connected to DC / DC converters respectively. When one battery pack under test is discharging, the released electrical energy is input to the other battery pack under test by turning on the other DC / DC converter, thereby enabling simultaneous discharge and charge tests on the two battery packs under test.
[0037] Compared to resistive discharge, this solution significantly reduces energy consumption in converting electrical energy into heat, thereby reducing energy waste and lowering cooling costs. Furthermore, this solution utilizes two connected DC / DC converters to enable the flow of electrical energy between the two battery packs under test. When one battery pack discharges, the released energy is used to charge the other, eliminating the need for multiple discharges and charges for each individual battery pack. This reduces the need for grid expansion, further lowering expansion costs and electricity expenses, and facilitating wider adoption.
[0038] In one embodiment, a first transmission line is provided between the first DC / DC converter 3 and the first battery pack under test 5, a second transmission line is provided between the second DC / DC converter 4 and the second battery pack under test 6, and a third transmission line connecting the first transmission line and the second transmission line is provided between the two DC / DC converters. Both the first DC / DC converter 3 and the second DC / DC converter 4 include a discharge state and a charging state, and the control module is configured such that when one DC / DC converter is in the discharge state, the other DC / DC converter is in the charging state.
[0039] When the first DC / DC converter 3 is in a discharging state, the second DC / DC converter 4 is in a charging state, and energy is input to the second battery pack 6 through the first battery pack 5 under test; when the second DC / DC converter 4 is in a discharging state, the first DC / DC converter 3 is simultaneously in a charging state, and energy is input to the first battery pack 5 through the second battery pack 6 under test.
[0040] The control module 9 controls the AC / DC converter 2 to shut down and turns on the first DC / DC converter 3 and the second DC / DC converter 4. The first battery pack under test 5 discharges and the second DC / DC converter 4 inputs electrical energy to the second battery pack under test 6, charging the second battery pack under test 6. This allows for simultaneous discharge and charging tests on both battery packs under test, and efficiently utilizes the electrical energy discharged by the first battery pack under test 5, which helps reduce energy loss. It also allows for bidirectional testing between the two battery packs under test, reducing the need for grid expansion and lowering expansion costs.
[0041] It is understood that although the first, second, and third transmission lines are not shown in the accompanying drawings, the connection between them via transmission lines is something that a person skilled in the art could set up based on the interconnection relationship described in this application.
[0042] Furthermore, BMS10 is connected to the first battery pack under test 5 and the second battery pack under test 6 respectively, and the charge and discharge data includes the state of charge of the first battery pack under test 5 and the state of charge of the second battery pack under test 6.
[0043] The BMS10 can be connected to the first battery pack 5 and the second battery pack 6 under test via electrical signals to monitor the battery packs under test. It should be noted that the state of charge (SOC) in this application refers to the SOC value.
[0044] This application's solution, by setting up a control module 9 and a BMS10, monitors the state of charge of the battery pack under test in real time during the testing process to ensure the smooth progress of the charging and discharging process. The control module 9 controls the activation of the first DC / DC converter 3 and the second DC / DC converter 4. During the charging and discharging process of the first battery pack under test 5 and the second battery pack under test 6, the BMS10 monitors the state of charge of the first battery pack under test 5 and the second battery pack under test 6 and transmits it to the control module 9 to determine whether the state of charge of the two battery packs under test is changing normally, thus ensuring the smooth progress of the testing process.
[0045] In one embodiment, the control module 9 is connected to the DC / DC converter. The control module 9 is configured to shut down the corresponding DC / DC converter in the discharge state and stop discharging when the state of charge of the battery pack under test in the discharge state reaches a preset lower limit state of charge.
[0046] The control module 9 can be connected to the DC / DC converter via electrical signals.
[0047] Preferably, a fourth power transmission line connected to the third power transmission line is provided between the AC / DC converter 2 and the DC / DC converter. The control module 9 is configured to turn on the AC / DC converter 2 and connect it to the DC / DC converter in the charging state after the battery pack under test in the discharging state stops discharging, and to replenish the battery pack under test in the charging state through the fourth power transmission line.
[0048] Discharge losses are inevitable during the testing process. For example, the first DC / DC converter 3 is controlled to be in a discharging state to perform a discharge test on the first battery pack 5 under test. At the same time, the second DC / DC converter 4 is controlled to be in a charging state to use the electrical energy released by the first battery pack 5 to charge the second battery pack 6 under test. When the state of charge of the first battery pack 5 under test reaches the preset lower limit of the state of charge, that is, the energy release test of the first battery pack 5 under test in this stage is completed. However, due to the electrical energy loss in the process, the second battery pack 6 under test has not yet been fully charged, and the energy storage test of the charged second battery pack 6 under test has not yet been completed. At this time, the first DC / DC converter 3 is turned off and the AC / DC converter 2 is turned on to continue to supply electrical energy to the second battery pack 6 under test until it reaches the preset upper limit of the state of charge, thus completing the energy storage test of the second battery pack 6 under test in this stage, that is, the charging test.
[0049] During the actual testing process, the first battery pack 5 and the second battery pack 6 were discharged in turn to carry out multi-stage testing, and the battery packs under test that were in the charging state at each stage were recharged as needed.
[0050] This application's solution uses BMS10 to monitor and acquire the state of charge (SOC) of the first battery pack 5 and the second battery pack 6 under test. During charging and discharging, when a preset lower SOC is reached, the corresponding DC / DC converter of the discharging battery pack is shut down, stopping the discharge. Since energy loss is inevitable during discharge, not all the released energy can be input to the other battery pack under test. To ensure the accuracy of the test results, the charging battery pack under test is supplemented with power through the grid 1 to reach a preset upper SOC. The preset lower and upper SOC are pre-set according to the test requirements, such as setting the preset lower SOC to 10% or 20% and the preset upper SOC to 90% or 80%. The specific settings can be determined based on the actual test requirements.
[0051] In one embodiment, the battery pack under test includes an initial state, and the control module 9 is configured to turn on the AC / DC converter 2 and the first DC / DC converter 3 in the initial state, while turning off the second DC / DC converter 4, so that the first battery pack under test 5 is charged to a first upper limit state of charge.
[0052] Furthermore, BMS10 is configured to acquire the state of charge of the first battery pack under test 5 when the battery pack under test is in the initial state and feed it back to the control module 9. When the state of charge of the first battery pack under test 5 reaches the first upper limit state of charge, the control module 9 shuts down the AC / DC converter 2.
[0053] Initially, only one of the battery packs under test needs to be charged through the power grid 1 until it reaches the first upper limit state of charge. This first upper limit state of charge is typically greater than the previously mentioned preset upper limit state of charge. That is, during discharge, the energy of the first battery pack 5 does not need to be completely released; instead, it is released according to the preset lower limit state of charge set for the test, until it reaches the required preset lower limit state of charge. After the first battery pack 5 reaches the first upper limit state of charge, the AC / DC converter 2 is turned off, and the two DC / DC converters are turned on, initiating mutual charging and discharging between the two battery packs. When recharging is needed, the AC / DC converter 2 is used to recharge the battery packs back to the preset upper limit state of charge.
[0054] Preferably, both the first DC / DC converter 3 and the second DC / DC converter 4 are bidirectional DC / DC converters.
[0055] like Figure 1As shown, in this application, both the first battery pack 5 and the second battery pack 6 under test include: a battery stack, a positive electrode storage tank connected to the positive electrode of the battery stack and a negative electrode storage tank connected to the negative electrode of the battery stack, a valve and a circulation pump 7 located on the connection line between the positive electrode storage tank and the negative electrode storage tank and the battery stack, each battery stack is connected to a corresponding DC / DC converter, and the BMS10 is configured to acquire the state of charge of the two battery stacks during the test.
[0056] As shown in the figure, the first battery pack under test 5 includes a No. 1 battery stack 51, and the second battery pack under test 6 includes a No. 2 battery stack 61. The charging and discharging test of the No. 1 battery stack 51 and the No. 2 battery stack 61 is performed using the towing test system of this application to test the energy storage and release capabilities of the No. 1 battery stack 51 and the No. 2 battery stack 61.
[0057] Although the diagram does not label the positive and negative electrode storage tanks for the second battery pack 6 under test, it is understandable that the positive electrode storage tank is connected to the positive electrode of the No. 2 battery pack 61, and the negative electrode storage tank is connected to the negative electrode of the No. 2 battery pack 61.
[0058] In addition, the arrows on the lines connecting the fuel cell stack, the positive electrode storage tank, and the negative electrode storage tank in the diagram indicate the direction of electrolyte flow.
[0059] Preferably, the valve is a ball valve 8, and the ball valve 8 and the circulation pump 7 are always in the open state during the test. Electrolytes are stored in both the positive and negative electrode storage tanks. Keeping the ball valve 8 and the circulation pump 7 always open helps ensure the flow of the positive and negative electrode electrolytes throughout the test, thus improving test efficiency.
[0060] During the testing process of this application, the charging and discharging states of the corresponding battery packs under test are controlled by a DC / DC converter to test the energy storage and release capabilities of the battery stacks. Mutual charging and discharging tests are conducted using a towed structure of two battery stacks. For multiple test points on the production line, this method reduces the capacity requirement for each battery stack to charge simultaneously from the power grid, reducing the need for power expansion and lowering testing and electricity costs. Simultaneously, by rationally utilizing the released electrical energy during discharge to charge the other battery stack in the towed structure, energy utilization is improved, heat dissipation and cooling requirements are reduced, further lowering testing costs.
[0061] For any parts not mentioned in this application, existing technologies may be used or referenced.
[0062] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.
[0063] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.
Claims
1. A testing system for towed flow batteries, used to simultaneously perform charge-discharge tests on two flow batteries under test, characterized in that, The device includes an AC / DC converter connected to a power grid, a DC / DC converter connected to the AC / DC converter, and a battery pack under test connected to the DC / DC converter. The DC / DC converter includes a first DC / DC converter and a second DC / DC converter. The battery pack under test includes a first battery pack under test connected to the first DC / DC converter and a second battery pack under test connected to the second DC / DC converter. The first DC / DC converter is connected to the second DC / DC converter. It also includes a control module and a BMS connected to the control module. The BMS is connected to the battery pack under test. The BMS is configured to send the charging and discharging data of the battery pack under test during the charging and discharging process to the control module. The control module is configured to control the start-up of the AC / DC converter and the DC / DC converter based on the data obtained by the BMS.
2. The test system for towed flow batteries according to claim 1, characterized in that, A first transmission line is provided between the first DC / DC converter and the first battery pack under test, a second transmission line is provided between the second DC / DC converter and the second battery pack under test, and a third transmission line is provided between the two DC / DC converters, connecting the first transmission line and the second transmission line. Both the first DC / DC converter and the second DC / DC converter include a discharge state and a charging state, and the control module is configured such that when one of the DC / DC converters is in the discharge state, the other DC / DC converter is in the charging state.
3. The test system for towed flow batteries according to claim 2, characterized in that, The BMS is connected to the first battery pack under test and the second battery pack under test respectively, and the charge and discharge data includes the state of charge of the first battery pack under test and the state of charge of the second battery pack under test.
4. The test system for towed flow batteries according to claim 3, characterized in that, The control module is connected to the DC / DC converter. The control module is configured to shut down the corresponding DC / DC converter in the discharge state and stop discharging when the state of charge of the battery pack under test in the discharge state reaches a preset lower limit state of charge.
5. The test system for a towed flow battery according to claim 4, characterized in that, A fourth power transmission line is provided between the AC / DC converter and the DC / DC converter, which is connected to the third power transmission line. The control module is configured to turn on the AC / DC converter and connect it to the DC / DC converter in the charging state after the battery pack under test stops discharging in the discharging state, and to replenish the battery pack under test in the charging state through the fourth power transmission line.
6. The test system for towed flow batteries according to claim 1, characterized in that, The battery pack under test includes an initial state. The control module is configured to turn on the AC / DC converter and the first DC / DC converter in the initial state, while turning off the second DC / DC converter, so that the first battery pack under test is charged to a first upper limit state of charge.
7. The test system for a towed flow battery according to claim 6, characterized in that, The BMS is configured to acquire the state of charge of the first battery pack under test and feed it back to the control module when the battery pack under test is in the initial state. When the state of charge of the first battery pack under test reaches the first upper limit state of charge, the control module shuts down the AC / DC converter.
8. The test system for towed flow batteries according to claim 1, characterized in that, Both the first DC / DC converter and the second DC / DC converter are bidirectional DC / DC converters.
9. The test system for a towed flow battery according to claim 1, characterized in that, Both the first and second battery packs under test include: a battery stack, a positive electrode reservoir connected to the positive terminal of the battery stack, a negative electrode reservoir connected to the negative terminal of the battery stack, a valve and a circulation pump located on the connection lines between the positive electrode reservoir and the negative electrode reservoir and the battery stack, each battery stack being connected to the corresponding DC / DC converter, and the BMS being configured to acquire the state of charge of the two battery stacks during the test.
10. The test system for a towed flow battery according to claim 9, characterized in that, The valve is a ball valve, and both the ball valve and the circulating pump are kept open during the test.